JPS6041681B2 - Blast furnace gas dry dust removal system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a blast furnace gas dry dust removal system for the purpose of protecting an existing blast furnace gas line when a dry dust remover and a furnace top pressure power recovery turbine are installed in the existing blast furnace gas line. be.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

B gas discharged from the top of the blast furnace 1 passes through a coarse dust remover (dust catcher, etc.) 3 installed in the gas exhaust pipe 2, and then passes through a dry dust remover (dry electrostatic precipitator, bag filter, etc.) 4.
to go into. Then, after passing through an end pipe 7 from a bypass pipe 6 having a bypass pressure regulating valve 5 for adjusting the furnace top pressure, it is led to a gas holder, a boiler, a hot blast furnace, or a heating furnace. 8
is a top power recovery turbine installed in parallel with the bypass pressure regulating valve 5, which is constantly connected to the in-house power grid and has a heavy load. is supplied, and B gas is returned through a discharge pipe 10 that joins the outlet of the bypass pipe 6.

The inlet pipe 9 is provided with an inlet valve 11, an emergency valve 12, and a governor valve 13, and the discharge pipe 10 is provided with an outlet valve 14. A refrigerant injection device 1 having a refrigerant control valve 15 in the turbine outlet pipe 7
6 is provided, and is configured to inject refrigerant into subsequent gas pipes 6 and 7 including the bypass pipe when the turbine is stopped. A gas temperature detection sensor 17 is provided downstream of the refrigerant injection device 16, and is configured to control the refrigerant control valve 15 based on a temperature signal from this sensor. Note that adjusting the refrigerant injection device 16 after detecting the blast furnace gas temperature with the gas temperature detection sensor 17 inevitably causes a delay in response. The refrigerant control valve 15 is opened by inputting one of the closing signals of the shutoff valve 12 to the refrigerant control valve 15 via a control mechanism (not shown), and the refrigerant is sprayed into the exhaust gas, thereby responding. It eliminates delays. When the operating condition of the blast furnace 1 is normal, the furnace top discharge temperature of the blast furnace gas is 110~150℃, and the dry dust remover 4
Considering the heat dissipation up to this point, the outlet temperature of the dry dust remover 4 will be 1000 to 140°C. When the top power recovery turbine 8 is in operation, the bypass pressure regulating valve 5 is normally fully closed, and the pressure at the top of the blast furnace 1 is kept constant by the governor 13 in front of the turbine 8 or the movable stationary blades in the turbine 8. is controlled by. The outlet temperature T2 of the turbine 8 is expressed by the following equation, where the inlet temperature of the turbine 8 is T1 (assuming that there is no water condensation within the turbine). P1; Turbine inlet pressure P2; Turbine outlet pressure ηAd; Adiabatic efficiency k; Adiabatic index where:

Therefore, the 5B gas entering the turbine 8 at 140°C is
When the turbine inlet pressure is 1.5 kg/CrlG, it will be discharged at 69°C. The B gas that has entered the turbine 8 in this way varies depending on the turbine inlet temperature and inlet pressure, but if P1 is 1.0 to 2.5k9/CflG, the temperature decreases within the turbine 8 and approximately It is discharged at a temperature within the range of 10 to 80°C. In conventional steel works, piping systems for blast furnace gas are designed for blast furnace gas that has been cooled by a wet scrubber to a temperature of 300 to 70°C.

As shown in the figure, the wet scrubber is replaced with a dry dust remover 4,
If the bypass pressure regulating valve 5 such as a septum valve is closed and all or most of the blast furnace gas is passed through the turbine 8, there is no particular problem because the turbine outlet temperature will be about the same as the conventional piping temperature as described above. If 8 is stopped for some reason, the blast furnace gas will flow through the existing piping system at high temperature, causing problems with the thermal expansion of the piping and gas holder and the heat resistance of the packing and seal links. Therefore, in the present invention, as described above, the subsequent piping 6 including the bypass piping
, 7 is provided, and a gas temperature detection sensor 17 is provided in the piping 6, 7 downstream of this, and the refrigerant control valve 15 is operated to lower the gas temperature to the design temperature of the piping system. I try to keep it.

The process from turbine operation to turbine emergency stop and turbine startup is as follows.

a Turbine in operation → Turbine dangerous stop → Turbine stopped state.

The bypass pressure regulating valve 5 is opened in an emergency, and at the same time, the valve 1 is opened in an emergency.
2, and disconnect the generator load (also close the governor valve).
At the same time, the refrigerant control valve 15 is actuated by one of the actuation signals of these valves, thereby injecting the refrigerant into the end pipe 7.

Next, the temperature instruction signal 1 from the gas temperature detection sensor 17
8 controls the opening degree of the refrigerant control valve 15, thereby adjusting the amount of refrigerant jetted out and keeping the gas temperature below the design temperature of the piping. b Turbine startup The turbine 8 is started by opening the inlet valve 11, outlet valve 14, and emergency valve 12, and opening the governor valve 13 while throttling the bypass pressure regulating valve 5. let

When the rotational speed of the turbine 8 reaches a predetermined value, a load is applied. With this operation, the low-temperature gas that has passed through the turbine 8 is mixed with the high-temperature gas in the end pipe 7, and finally the end pipe 7 is filled with low-temperature gas. During this time, the refrigerant control valve 15 is controlled by the temperature instruction signal 18 from the gas temperature detection sensor 17, the amount of refrigerant injected from the refrigerant injection device 16 decreases, and finally the injection is stopped. Note that when the stator vanes of the turbine 8 are made variable to have the function of a governor valve, the governor valve 13 is replaced with the variable stator vanes of the turpin 8. In the figure, the refrigerant injection device 16 is connected to the unpiped end 7.
Although it is provided in the bypass piping 6, it may also be provided in the bypass piping 6.

In particular, when it is provided in front of the bypass pressure regulating valve 5, there is an advantage that it can also serve as a cleaning device for the bypass pressure regulating valve 5. As described above, according to the present invention, the refrigerant injection device is actuated by the bypass pressure regulating valve open signal at the time of an emergency turbine stop or the close signal at the time of emergency or valve shutoff, and the temperature instruction signal from the gas temperature detection sensor. The refrigerant can be supplied into the subsequent gas piping including the bypass piping, and the gas temperature can be kept below the design temperature of the piping.

This makes it possible to protect the piping and gas holder against heat resistance.

[Brief explanation of the drawing]

The drawing is a system diagram showing one embodiment of the present invention. 1...Blast furnace, 3...Coarse dust remover, 4.
...Dry dust remover, 5-I-1●Bypass pressure regulating valve,
6・I・◆・Bypass piping, 7...end unpiped,
8... Furnace top pressure power recovery turbine, 12...
...Emergency valve cut, 15...Refrigerant control valve, 16.
. . . Refrigerant injection device, 17 . . . Gas temperature detection sensor, 18 . . . Temperature instruction signal.

Claims (1)

[Claims] 1 A system in which a blast furnace, a coarse dust remover, a dry dust remover, and a furnace top pressure power recovery turbine are arranged in this order, and a bypass pressure regulating valve is installed in the middle of a bypass pipe arranged in parallel with the turbine, and An emergency valve is provided in the middle of the introduction pipe that is branched and introduces the exhaust gas into the turbine, and a refrigerant injection device having a refrigerant control valve is provided in the subsequent gas piping including the bypass pipe having the refrigerant control valve, and the refrigerant is A temperature detection sensor linked to the refrigerant injection device is provided in the piping downstream of the injection device, and the refrigerant of the refrigerant injection device is controlled by an open signal of the bypass pressure regulating valve at the time of emergency stop of the turbine or a close signal of the emergency valve shutoff. 1. A blast furnace gas dry dust removal system, characterized in that a valve is opened to inject refrigerant into the gas, and the amount of refrigerant injection is controlled based on a temperature instruction signal from the temperature detection sensor.